Recent events in the hundred day war between the Coalition Forces and Iraq demonstrated that terrorism in the form of setting oil wells on fire can have severe economic and environmental consequences. Of course the burning of crude oil that otherwise would be used locally or sold on the world market damages the producer's economy, and can have an impact on the world market price of oil where the producer has substantial sales. The thick black cloud of smoke that is produced particularly when a large number of wells are on fire, severely reduces the amount of sun light that reaches the ground. This can have immediate as well as long term effects on the ecology of the region that is covered by smoke. Therefore, it is imperative that the fire of any burning oil well be extinguished, and the well put back into production, as quickly as possible. Of course this holds true for any land-based or offshore well that is burning out of control.
An oil well fire is not easy to extinguish. A huge and extremely hot flame is produced which has the general characteristics of the flame of a blow torch due to the high velocity of the flow of oil or gas as it escapes from the top of the well into the atmosphere. There is a vertical region immediately above the top of the casing where the oil flows unignited, i.e. before the flame front begins. A common method of putting out this type of fire is to cool the top of the well and the surrounding areas by large amounts of sprayed water, move a vehicle that has an explosive charge on the end of a long boom close enough so that the charge is adjacent the vertical region mentioned above, and then set off the charge. The explosion of the charge uses substantially all available oxygen in the region between the top of the well and the flame front so that the flame is extinguished. Then a special valve head is lowered over the top of the well casing and clamped in place. One or more normally open valves in the head can be closed by remote control to shut in the well.
Although the foregoing technique has been widely used, it has a number of shortcomings. The principle disadvantage is that there is a relatively long time lapse between the event of exploding the charge to extinguish the flame, and the setting of the valve head on the top of the well. At any time, the fire can be rekindled due to hot metal parts and debris in the area, and the flame extinguishing procedure then will have to be repeated. This time lapse is extremely dangerous to persons who are operating the equipment, and might be near the well when it reignites. Another disadvantage is that the explosive may not extinguish the flame, or extinguish it only temporarily, both of which produce delay and continuing dangerous conditions.
An object of the present invention is to provide a new and improved method and apparatus for quickly shutting off the flow of oil from a burning well.
Another object of the present invention is to provide a new and improved process for cutting off the top of the casing and setting a packer in the casing below the cut in a substantially continuous process and operation that can be quickly carried out.